[nnc] Move batchnorm to operators library (#59992)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59992
Wrapped batch norm in function `computeBatchNorm`.
ghstack-source-id: 131407851
Test Plan: CI
Reviewed By: ZolotukhinM
Differential Revision: D29116661
fbshipit-source-id: 2873a9a3e70f31db1988787160fc96c388ea3d4a
